Fun With var

A live-coding talk where I show off all you need to know about var in Java. And then some.

Since Java 10 you can use var to let the compiler infer a local variable's type:

var users = new ArrayList<User>();

And that's pretty much it, right? Surprisingly, no! There are a lot of details to consider...

  • is this JavaScript?!
  • how exactly is the type inferred?
  • where can I use var and what should I look out for?
  • won't this lead to unreadable code?

... and a few fun things to do with var...

  • playing with anonymous classes (don't!)
  • faking traits (don't!)
  • faking intersection types (do!)

After this live-coding deep dive into var, you'll know all about Java 10's flagship feature.

Slides

Here's the current version of the slides.

I also embedded them below. If they're focussed, you can navigate with arrow keys or swipes (they're two-dimensional, with chapters on the horizontal axis and chapter content layed out vertically). Use Page Up/Down for linearized order and ? for more shortcuts.

Video

Here's a good recording of the talk. I hope you'll like it.

Always embed videos

(and give me a cookie to remember - privacy policy)

Watch on YouTube

Past Presentations

I gave this talk a few times before. See below for links to slides (as they were at that very event), videos, and other information.

2019

Wed, Jul 10th, 19:00 Europe/BerlinFun with var
at JUG Darmstadt
TU Darmstadt, S2|02 (Robert-Piloty-Geb.), Raum C110, Hochschulstr. 10
Fri, Apr 26th, 11:05 Europe/KievFun With var
at JEEConf
Kiev, Mercure Congress Hall, Track D

2018

Wed, Dec 12th, 17:00 UTCFun with var in Java 10
Thu, Nov 8th, 16:50 Europe/AmsterdamFun with var in Java 10
at J-Fall
Pathé Ede, Zaal 1